feat: add DuckDB to onprem/database

diagrams/onprem/database.py

@@ -36,6 +36,10 @@ class Druid(_Database):
     _icon = "druid.png"
 
 
+class Duckdb(_Database):
+    _icon = "duckdb.png"
+
+
 class Hbase(_Database):
     _icon = "hbase.png"
 

docs/nodes/onprem.md

@@ -203,6 +203,9 @@ Node classes list of the onprem provider.
 <img width="30" src="/img/resources/onprem/database/druid.png" alt="Druid" style="float: left; padding-right: 5px;" >
 **diagrams.onprem.database.Druid**
 
+<img width="30" src="/img/resources/onprem/database/duckdb.png" alt="Duckdb" style="float: left; padding-right: 5px;" >
+**diagrams.onprem.database.Duckdb**
+
 <img width="30" src="/img/resources/onprem/database/hbase.png" alt="Hbase" style="float: left; padding-right: 5px;" >
 **diagrams.onprem.database.Hbase**, **HBase** (alias)